EUV litho source is much brighter, says Ushio

LONDON – Xtreme Technologies GmbH (Aachen, Germany) has reported a doubling of the brightness of its laser-assisted discharge plasma (LDP) illumination source for extreme ultraviolet (EUV) lithography. The company, a wholly owned subsidiary of Ushio Ltd. (Tokyo, Japan), has reported it has an output of 30 watts measured at the intermediate focus under a 100 percent duty cycle.

In addition the company has claimed that technologies applied will let the brightness be increased yet further and that it has a prototype 100-W source.

The step is important because EUV lithography scanners, from companies such as ASML Holding NV (Veldhoven, The Netherlands), are currently limited in the number of wafers that can be processed in a given time by the illumination and are described as uneconomic at previous levels. A source with 100W brightness that would allow 60 wafers per hour or the 250W brightness that would allow 125 wafers per hour.

The higher the throughput the lower the cost of ownership and the more economic EUV lithography becomes. A throughput of 100 wafers per hour is a benchmark chipmakers have become used to with previous generations of 193-nm wavelength optical lithography equipment.

Xtreme reported the latest development at the 2011 International Symposia on Extreme Ultraviolet Lithography and Lithography Extensions, held in Miami, Florida between Oct. 17 and 21, 2011, Ushio said.

Xtreme had achieved an output of 15W at an intermediate focus point under a duty cycle of 100 percent in February 2011. The move up to a stable output of 30W was achieved by solving issues around debris and thermal processing Ushio said while claiming that the current solutions will scale to higher output.

"We have already confirmed an output equivalent to 100 watts at an intermediate focus with a prototype light source. We have reached the stage of achieving an output of 30 W at an intermediate focus with continuous emission," said Masaki Yoshioka, executive vice president and chief technology officer of Xtreme Technologies, in a statement.

The IMEC research institute (Leuven, Belgium) has an NXE:3100 preproduction EUV lithography scanner from ASML with a Ushio discharge-produced plasma (DPP) source but is only running a few wafers through the machine each hour.

"output equivalent" is not same as actual output. And the intermediate focus power has to increase to keep the same throughput for smaller features. It is not a fixed 100 W target.
EUV production is such a highly inefficient process, the very opposite of green. So much energy going in, only for low efficiency production of radiation at many wavelengths over a broad range, all of which (except one) are then re-absorbed (i.e., wasted).
At least excimer lasers produce a very narrow wavelength range.